Structure and conductivity of yttria and scandia‐doped zirconia crystals grown by skull melting

In this paper a detailed study of the (ZrO₂)_1‐x(Y₂O₃)_x (x=0.025–0.15), (ZrO₂)_1‐x(Sc₂O₃)_x (x = 0.06 – 0.11) and (ZrO₂)_1‐x‐y(Sc₂O₃)_x(Y₂O₃)_y (x=0.07 – 0.11; y=0.01 – 0.04) solid solution crystals grown by skull melting technique is presented. The structure, phase composition, and ion conductivity of the obtained crystals were investigated by X‐ray diffraction, transmission electron microscopy, Raman scattering spectroscopy, and impedance spectroscopy. Maximum conductivity as (ZrO₂)_1‐x(Y₂O₃)_x and (ZrO₂)_1‐x(Sc₂O₃)_x solid solution crystals is observed for the compositions containing 10 mol% stabilizing oxide, and the conductivity of 10ScSZ is ~3 times higher than for 10YSZ. Experiments on crystal growth (ZrO₂)_1‐x‐y(Sc₂O₃)_x(Y₂O₃)_y solid solutions showed that uniform, transparent crystals 7Sc3YSZ, 7Sc4YSZ, 8Sc2YSZ, 8Sc3YSZ, 9Sc2YSZ, 9Sc3YSZ, 10Sc1YSZ, and 10Sc2YSZ are single phase crystal containing t″ phase. It is established that a necessary condition of melt growth of (ZrO₂)_1‐x‐y(Sc₂O₃)_x(Y₂O₃)_y single‐phase crystals is the total concentration of the stabilizing oxides from 10 to 12 mol%. The addition of Y₂O₃ affects the (ZrO₂)_1‐x‐y(Sc₂O₃)_x(Y₂O₃)_y solid solution conductivity different ways and depends on the Sc₂O₃ content in the starting composition. The effects of structure, phase composition, concentration, and type of stabilizing oxides on the electrical characteristics of obtained crystals are discussed.     

Change in the mechanism of conductivity in ZrO<Subscript>2</Subscript>-based crystals depending on the content of stabilizing Y<Subscript>2</Subscript>O<Subscript>3</Subscript> additive

The interrelationship between the structure, phase composition, and transport characteristics of solid electrolytes based on ZrO₂ has been studied as dependent on the content of stabilizing Y₂O₃ additive. It is established that twin boundaries do not lead to the appearance of additional mechanism of ionic conductivity acceleration in ZrO₂–Y₂O₃ crystals. The maximum conductivity has been observed in ZrO₂–(8–10) mol % Y₂O₃ crystals containing a t” phase, in which oxygen atoms are displaced from high-symmetry positions characteristic of the cubic phase.     

Effect of Y<Subscript>2</Subscript>O<Subscript>3</Subscript> stabilizer content and annealing on the structural transformations of ZrO<Subscript>2</Subscript>

The structure of partially stabilized zirconia crystals has been studied by transmission electron microscopy before and after annealing. Structural characterization of Y₂O₃-doped (2.8 to 4 mol %) zirconia before annealing showed that all of the samples consisted of twin domains whose size was dependent on the stabilizer content. Annealing at 2100°C increased the domain size in the composition range 2.8–3.7 mol % Y₂O₃ and reduced it at 4 mol % Y₂O₃. These structural changes allowed us to determine the position of the representative point relative to the phase boundary in the equilibrium phase diagram of the system.     

Development of natural convection in a liquid heated by the front of self-propagating high-temperature synthesis (SHS)

The process of development of free convection in a liquid heated by a moving combustion front is considered. The emphasis is on the dynamics of development of the process.Moscow Power Institute, Kazan' Branch. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 63, No. 4, pp. 400–403, October, 1992.     

Measurement of the turbulent flow structure of submerged jets of polymer solutions

Measurements are made of the average and pulsation velocities, the energy spectra, and the coefficients of turbulent diffusion during the flow of submerged jets of water and solutions of polyethylene oxide, Na-CMC, and guar gum.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 25, No. 6, pp. 977–986, December, 1973.     

Effect of the Phase Composition and Local Crystal Structure on the Transport Properties of the ZrO2–Y2O3 and ZrO2–Gd2O3 Solid Solutions

Russian Microelectronics - The results of investigating the crystal structure, ionic conductivity, and local structure of the (ZrO2)1 –x(Gd2O3)x and (ZrO2)1 –x(Y2O3)x (x = 0.04, 0.08,...     

Raising the fatigue strength of a construction by local laser heating

A method is proposed for raising the fatigue strength of a construction by inducing residual stresses by local heating with a high-power pulsed laser. Fatigue failure can be slowed or eliminated, as can the formation of fatigue defects, if a pattern of compressive residual stresses is produced in the most readily damaged zones. Experiments have been done on how laser heating affects the fatigue strengths of planar specimens and fatigue crack growth. Finite-element calculations have been used to examine the effects of the heating parameters on the residual stresses.Translated from Problemy Prochnosti, No. 4, pp. 10–17, April, 1995.     

Preparation and properties of Y<Subscript>2</Subscript>O<Subscript>3</Subscript> partially stabilized ZrO<Subscript>2</Subscript> crystals

We have studied the effect of composition and growth conditions on the structure and properties of 2.5–5 mol % Y₂O₃ partially stabilized ZrO₂ crystals grown by directional solidification in a cold-wall crucible. The phase composition and density of the crystals have been determined. The crystals are shown to be uniform in composition, with local changes in Y₂O₃ content within ±0.5 mol %. The dimensions and quality of the single crystals are influenced by the growth conditions.